1. Field of the Invention
The present invention relates to a method and apparatus for controlling the winding of a roving in a flyer frame, where the roving from a front roller is wound on a roving bobbin, while the direction of the movement of a bobbin rail is alternately switched.
2. Description of Related Art
In a spinning factory, flyer frames produce roving bobbins, which are conveyed to fine spinning frames, where the roving from the bobbins are subjected to a fine spinning process for producing spun yarns on cops, while emptied roving bobbins at the fine spinning frames are returned back to the flyer frames for re-use. Various automated operations have been developed in this field. Namely, in order to obtain an automated conveyance of full bobbins from the flyer frames to the fine spinning frames and of empty bobbins from the fine spinning frames to the flyer frames, a system has proposed, wherein a rail conveyor is provided for conveying full bobbins, being carried by bobbin carriages in a suspended condition, from the flyer frames to auxiliary rails of creels of the fine spinning frames, almost emptied bobbins held by the creels are replaced by the conveyed full bobbins, while rovings from the full bobbins are pieced to respective ends of rovings supplied to respective spinning units of the fine spinning frames, a roving stripper is provided for stripping residual roving on the almost emptied bobbins after the replacement, and the completely emptied bobbins are returned to the flyer frames for re-use.
In this system, the piecing of the full bobbins can be automatically executed as disclosed by Japanese Un-Examined Patent Publication No. 62-53425 and Japanese Un-Examined Patent Publication No. 64-52828. In such an automated piecing apparatus, an end of the roving on a bobbin is found and held by an air sucker, and a end of the roving shaped as a pointed brush shape is, while being held by a nipper, moved so as to be contacted with a roving supplied to a spinning unit from the almost emptied bobbin. A disengagement of the nipper causes the roving end of the full bobbin to be freed, causing it to be entrained by the supplied roving from the almost emptied bobbin to the spinning unit, thereby the roving from the full bobbin to be pieced to the roving from the emptied bobbin. Finally, the roving from the almost emptied bobbin is broken. In order to execute this kind of the piecing properly, it is required that the end of the roving in a full bobbin should be located on a predetermined vertical position, which allows the end of the roving to be positively engaged by the sucker. It is also required that the amount of the roving on a bobbin is fixed to a predetermined amount which corresponds to a predetermined length of a spun yarn produced by the following fine spinning process and corresponds to the amount of the spun yarn wound on a desired number of full cops. This latter requirement is generated from a necessity for reducing the amount of waste roving to be stripped from emptied roving bobbins when a doffing operation for exchanging the emptied bobbin with full bobbins is, from the view point of efficiency of automation, carried out simultaneously for all of the spindles in a flyer frame or for all of the spindles located on one side of the flyer frame.
In order to satisfy the above requirements, Japanese Un-Examined Patent Publication No. 3-180525 and Japanese Un-Examined Patent Publication No. 3-33230 disclose methods for winding a roving in a flyer frame, wherein a provision is made as to a device (encoder) for measuring the amount of roving to be issued and a device (encoder) for measuring the vertical position of a bobbin rail, and a residual amount of roving up to a full bobbin state is calculated as a predetermined amount of roving corresponding to the full bobbin state, minus the actual amount of roving wound on a bobbin at the instant. When this residual amount reaches a predetermined amount almost the same as the full bobbin state, a prediction is made, based on the actual position of the bobbin rail detected by the bobbin rail position detector at the instant, as to the position of the roving the full bobbin state. When it is determined that the predicted position of the roving at the full bobbin state is within a permissible range, switching of the bobbin rail up to the full bobbin state is effected at normally selected points. However, when it is determined that the predicted position of the roving upon the full bobbin state is out of the permissible range, switching points, which are different from the normally selected points and which are for causing the roving to be located in the permissible vertical range upon the full bobbin states are calculated. Thus, the switching of the bobbin rail up to the full bobbin state is effected at a different switching point, so that, upon the full bobbin state, the end of the roving is located within the permissible range of the vertical position. As a result, a full bobbin with the desired amount of roving as wound is obtained while the end of the roving is located at a position in the permissible vertical range.
However, the prior art is defective in that a process for controlling the winding of the roving is complicated due to the fact that a position of the roving end upon the full bobbin state is predicted when a residual amount of the roving is equal to a preset value, that positions of switching of the movement of the bobbin rail, which are different from normal positions, are calculated when it is determined that the predicted position is out of a permissible range, and that the bobbin rail is switched at the calculated positions by detecting the latter.
The prior art is defective also in that an encoder (sensor) is necessary to continuously monitor the vertical position of the bobbin rail, since a control is done so that the bobbin rail is reciprocated between varied vertical positions which are to be sensed.